Swimming pool apparatus



Jan. 16, 1968 W A, VAN DEN BROEK ET AL 3,363,766

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SWIMMING POOL APPARATUS Filed June 22, 1964 6 Sheets-Sheet s INVENTORSBY/ra .fz/Verma ATTOR YS United States Patent G 3,363,766 SWIMMING PULAPPARATUS William A. van den Broek, Buckingham, and ira Siiverman,Chaifont, Pa., assigner-s to Sylvan Pools, inc., Doyiestown, Pa., acorporation of Pennsylvania Continuation-impart of application Ser. No..222,26,

Sept. 11, i962. This application .inne 22, 1964, Ser.

This application is a continuation-in-part of application Ser. No.222,826, filed Sept. 11, 1962, now Patent 3,139,067, issued June 30,1964.

This invention pertains to swimming pool water treatment apparatus. Moreparticularly, it pertains to unitary apparatus which combine thefunctions of heating and filtering. In brief, it pertains to swimmingpool filterheater combinations.

The utility of, and need for, swimming pool filters has long beenrecognized. With such apparatus, fine foreign matter can be removed fromwater and original clarity maintained and restored. Often, in connectionwith a type of swimming pool filter known as a sand filter or sand andgravel filter, chemical additives, such as fiocculents, are used toincrease the total effectiveness of filtration. Filters are, therefore,essential items of equipment in pools where water is recirculated andwhere the only fresh water added during the swimming season is thatwhich replaces evaporative or overflow losses.

Less essential to pool operation, but of increasing importance, areswimming pool water heaters. These devices enable the season for use ofoutdoor pools to be extended from early spring to late fall. Unlikedomestic hot water heaters, where a relatively small quantity of wateris to be heated through a large number of degrees (eg. from ambient to140 E), these heaters heat large volumes of water through a relativelysmall number of degrees. In typical applications, heaters are used tomaintain `swimming pool temperatures in the range of 75-80 F., whendaily average or mean ambient temperatures are as low as 60 F.

Customarily the filtration and heating funuctions are performed byseparate, unrelated units-a filter and a heater.

Filters used in swimming pool work are of two basic types. The firsttype is a filter, commonly known `as a sand filter or sand and gravelfilter, which contains silicious material such as, for instance, sand ormixtures of sand and gravel. In these filters, the interstices betweenthe ne sand particles perform the actual filtration. As the filter isused, dirt builds up in the sand and this dirt is removed periodicallyby reversing the direction of fiow and backwashing the dirt into a`sewage system.

A second type of filter, commonly used, is known as a diatomaceous earthfilter. In this type of filter, mechanisms are provided which cansupport a coating of diatornaceous earth. These filters are pre-coatedwith diatomaceous earth which builds up on the surface of supportingelements (eg. bags, leaves made of screen, etc.). It is the coating ofdiatomaccous earth, containing fine interstices vas it does, which doesthe actual filtration, the understructure only supporting the coatingand keeping the diatomaceous earth intact. Periodic additions ofdiatomaceous earth present new and fresh filter surfaces to the liquidcoming through and the process is repeated until the coating becomes sothick that the hydraulic pressure drop across the filter elements isunmanageable. At that time the filter is physically cleaned and the old,dirt-laden diatomaceous earth removed.

Our prior application Ser. No. 222,826 filed Sept. 11, 1962, now Patent3,139,067, issued June 30, 1964, pertains to a filter-heatercombination. This application is a ICC continuation-in-part thereof. Inthat patent a filter-heater combination is disclosed in which an annularsand filter is mounted coaxially about a water heater core. Flow is fromthe swimming pool through the filter and thence, via the heater, back tothe swimming pool. In other words, it discloses filtration followed byheating as used, specifically, with a sand filter.

The instant application is directed to filter-heater combinationswherein filtration can be performed subsequent to heating, wherein thewater heater can be located concentrically about a filter core andwherein, further, diatomaceous earth filters as well as sand filters maybe utilized.

Accordingly, it is an object of the invention to provide a combinationfilter-heater which can heat and filter lsimultaneously and perform bothfunctions with high efeiency.

It is also an object of the invention to provide filterheatercombinations wherein filtration may be performed prior to heating and/orvice versa.

An additional object of the invention is to provide filter-heatercombinations wherein the combustion chamber or water heating portion ismounted concentrically about the filtration portion.

It is also an object of the invention to provide a filterheatercombination wherein the filter is of the diatomaceous earth type andwherein, further, the number of square feet of effective filter surfacecan be varied to suit the application of the unit.

It is also an object of the invention to provide an improvedfilter-heater combination wherein filtration can be performed in arelatively shallow depth of silicious filter medium, thus makingpossible construction of a unit having a relatively low height.

Another object of the invention is to provide an improved filter-heatercombination wherein a substantial portion of the heat exchange means isreadily renewable and replaceable.

Provision of a combined filter-heater wherein by-pass means are providedfor adjusting the amount of the water being heated while keeping theamount of water being filtered constant are also an object of theinvention.

An additional object of the invention is to provide an apparatus of thetype `described wherein control of outlet water temperature is accurateand control of gaseous fuel j is safe, utilizing no complicated orsophisticated coinponents liable to be a source of further maintenanceand adjustment problems.

It is also an object of the invention to provide filterheatercombinations which can utilize a wide variety of fuels.

Also, among the objects of the invention, is the provision of swimmingpool filter-heater combinations wherein a novel underdrain or collectoris employed to minimize silicious filter medium depth and to allow forhigh capacity emcient filtration in low units.

A further object of the invention is to provide a single piece ofapparatus which will serve as a filter, a water heater, a pump mount orbed plate and which will include self-contained control devices so thatthe totality of the apparatus can be inserted in swimming pool pipingand need only be connected to energy sources to be rendered operational.

`Other objects of the invention are to provide irnproved apparatus ofthe character described which are sturdy in construction, economical toproduce and install, and highly efficient in operation.

These and other objects of the invention will be apparent to thoseskilled in the art from a consideration of the description whichfollows, when read in conjunction with the accompanying drawings, inwhich:

FIGURE 1 represents a sectional view of a filter-heate combination ofthe invention, of the sand type, having an annular filtration sectionand an axial water heating section, wherein heating is followed byfiltration.

FIGURE 2 is a modified top plan view of the filterheater combination ofFIGURE 1.

FIGURE 3 represents a fragmentary elevational view of a heater by-passarrangement useful in conjunction with those filter-heater combinationsof the invention having axial water heating sections such as, forexample, the embodiment shown in FIGURES l, 2, 11 and 13.

FIGURE 4 represents a sectional View of a filter-heater combination ofthe invention, of the sand type, having an axial filtration section andan annular water heating section, wherein filtration is followed byheating.

FIGURE 5 represents a fragmentary section taken on line 5 5 of FIGURE 4.

FIGURE 6 represents a fragmentary sectional View of a filter-heatercombination of the invention, of the sand type, having an axialfiltration section and an annular water heating section, wherein heatingis followed by filtration.

FIGURE 7 represents a fragmentary section taken on line 7-7 of FIGURE 6.

FIGURE 8 represents a sectional view of a filter-heater combination ofthe invention, of the diatomaceous earth type, having an axialfiltration section and an annular water heating section, whereinfiltration is followed by heating.

FIGURE 9 represents a sectional view of a filter-heater combination ofthe invention, of the diatomaceous earth type, having an axialfiltration section and an annular heating section, wherein heating isfollowed by filtration.

FIGURE 1() represents a section taken on line .1G- 10 of FIGURE 9 and isalso generally representative of a typical section through the types offilter-heaters shown in FIGURE 8.

FIGURE 1l represents a sectional view of a filterheater Combination ofthe invention, of the diatomaceous earth type, having an annularfiltration section and an axial water heatin-g section, whereinfiltration is followed by filtration.

FIGURE 12 represents a section taken on line 12-12 of FIGURE 1l.

FIGURE 13 represents a sectional view of a filterheater combination ofthe invention, of the diatomaceous earth type, having an annularfiltration section and an axial water heating section, wheerinfiltration is followed by heating.

FIGURE 14 represents a fragmentary section taken on line 14-14 of FIGURE13.

Referring now to the drawings, wherein like numerals designate likeparts, it will be observed that the filterheater combination comprises ashell A having within it a filter section B and a water heater orcombustion chamber C. Calorie energy for the heater of chamber C issupplied by a burner assembly D and fuel fiow to the burners iscontrolled by thermostatic controller E.

Referring now to FIGURES 1 and 2 it will be observed that the embodimentof the invention shown therein includes a shell A which comprises avessel having a cylindrical wall portion to which is affixed a top 11,preferably dished, and a bottom 12 which is also preferably dished toprovide smooth internal corners and thus prevent hydraulic turbulence.Top 11 and bottom 12 are fixed to wall 10 by welding, as is customary inthe fabrication of pressure vessels built according to the A.S.M.E. codefor pressure vessels. Top 11 is provided with a central circular cut-outto which is affixed a riser 13 capped as at 14 in any suitable mannerwith an annular cap. The shell A is coaxially mounted on, affixed to andsupported by combustion chamber or heater section C. Chamber C includescylindrical sidewalls 15, a fiat foraminous bottom 16 affixed theretowhich contains a plurality of variable diameter air-inlet orifices 17, ahead 18, preferably dished, and a chimney 19 which is 4 i mounted on acut-out in head 18 and is capped by a draft hood Zti. Chimney 19 ispreferably coaxially mounted within riser 13. Cap 14, which is annularin configuration, abuts the exterior of the chimney. The entire assemblymay be supported by a plurality of legs 21, in which case, combustionair can be supplied through inlets 17 as indicated by the arrows.However, alternate air-inlets 22 are provided in the lower portion ofsidewall 15 and, if desired, the unit can be mounted directly on theground, without legs 21, and total combustion air requirements suppliedby inlets 22 as indicated by the arrows with inlets 17 renderedinoperative.

Chimney 19 may be provided with a plurality of internal baffles orretarders 23 which insure more efficient combustion and lower stackedoutlet temperatures. The baffles may be formed of a single piece havinga helical configuration or of a plurality of separate units.

The annular space between the exterior of water heater or combustionchamber C and the interior of shell A defines and constitutes filtersection B. It should be noted immediately that the net effectivecross-section of this filter section, proximate the top of sidewalls 15,is far less than the cross-section above dished head 18. Consequently,when water moves downward (with reference to FIG- URE 1) there is anincrease in velocity as it enters the narrowed ann'ulus between wallportion l() and combustion chamber sidewalls 15. The advantage of thisphysical design consideration, las related to high filtration capacity,will be discussed below.

Section B is filled with a silicious filtration medium 24 which extendsdownward from water-filter medium interface 25. The bottom of section Bis provided with a high capacity collector 26. This toroidal collector,of novel design, is ring-shaped in plan view and circular incrosssection. While it may be made of perforated metal, it is preferablyfabricated of a synthetic corrosion-resistant material such as, forexample, a long chain polyamide of the nylon type. The sleeve may beformed of an inner and outer layer of material reinforced and spacedapart by a metal Wire spider 27 which gives it rigidity and prevents itscollapse. At at least one point on its perimeter, collector 26 isprovided with an outlet fitting or transition piece 28 which, in turnremovably connects to a conduit 29 which leads to thermostaticcontroller E.

Water heater or combustion chamber C contains an helical heating coil 30suitably removably mounted coaxially therein. The coil 30 terminates atone end in a goose-neck riser 31 which penetrates head 18 and dischargeswithin filter section B above interface 25. The other end of the coil,its feed end, connects to a conduit 32 one end of which penetrateschimney 19 and is encapsulated thereby as it drops into the section ofthe chamber below head 18.

Mounted on the shell A, as with bracket or Weldment 33 is a pump 34which may be of any conventional type including, preferably,self-priming centrifugal. Pump 34 takes its suction from the poolthrough suction line 35 and discharges via conduit 32, helical coil 3f)and riser 31 into filter section B.

The hydraulic circuit, when the unit is heating and filtering may besummarized as follows: The pump 34 takes water from the pool throughsuction line 35 and pumps through conduits 32, coil 30 and riser 31 intofilter section B. Water flows downward, past interface 2,5, through thefilter medium 24 and thence into collector 26. Water leaving thecollector through transition piece 28 enters conduit 29 and goes fromthere into the body of thermostatic controller E. It is thence returnedto the pool through discharge line 36. It should be noted that anyexpension of liquid (eg. as by heating during periods when the pump isnot running) merely causes the incremental volume of liquid to flow tothe pool through the unobstructed non-valved fiow path just described.

The lter medium is backwashed in a conventional manner by reverseflushing with a stream of water and running the effluent to a sewer.Auxiliary piping for supplying wash water to the collector via conduit29 and for removing eiiluent to the sewer from above interface 25, aswell as a multi-port valve for use during the backwash period areconventional, form no part of the instant invention and are,accordingly, not shown.

The thermostatic controller E is a conventional unit such as is soldunder the trademark Unitrol by the Grayson Controls Division of theRobertshaw-Fulton Controls Company and are described fully, inter alia,in their bulletins 28-050-O046 and 28-050-0069D as well as specificallyin U.S. Patent Nos. 2,953,937 and 2,982,148. Briefly reviewing itsoperation, it uses water temperature as a parameter for controlling gasflow while at the same time supplying a pilot light quantity of gas tothe burners, independent of temperature variations. It furtherincorporates manual on-off features and fail-safe mechanisms whichdetection the absence of llame and shut olf the gas supply in such anevent. An advantage of the instant invention, compared to the prior art,is its ability to use such relatively standard controls rather thancombinations of relays, solenoid valves and remote sensors. The logic ofcontrol will be discussed in more detail below.

Returning now to the description of controller E, it comprises `a bodyor housing 37 containing an integral water passage including an inlet 38and an outlet 39, to which discharge line 36 is connected. As can beseen in the drawing, heated water returning to the pool passes throughthis passage. A bi-metallic element extends into the water passage :andsenses the temperature therein. Fuel gas (e.g., natural or manufactured)from main gas line 4t) enters the controller through gas port 41. Withinthe unit, the gas flow is split into a pilot stream and a burner feedstream, the former being conveyed to the pilots by pilot line 42 and thelatter iiowing to the burners via feed line 43 as indicated by thearrow.

The burner, indicated generally as 44, may be suitably mounted withinthe combustion chamber, as on header 45. A preferred burner is made ofcast iron with annular ports which distribute an even .and continuoushalo pat tern flame concentrated over predetermined portions of coil 30.The pilot associated with each burner may be side mounted for quicklighting and the pilot llame is not affected by olf and on actions ofthe burner. It is obvious that other sources of fuel such as oil andelectricity may, with suitable modifications, be utilized.

Turning now to a discussion of the apparatus and its superioritycompared to the prior art apparatus, consider iirst the filtrationfunction. The filter medium 24 is tine sand. Such material is used inconventional sand :and gravel lters but in these lters is supported bycoarse sand which in turn is supported by a bottom layer of pea gravel.This arrangement equalizes hydraulic resistance over the cross-sectionof the iilters and yet, just the fine sand performs the filtration. Inthe embodiment of the invention shown, the collector 26 is of extremelylarge effective area and because of its annular shape presents a uniformhydraulic resistance at any point in the bottom of the filter section B.Bottom 12 supports the sand and thus the two functions of theconventional gravel bed (i.e. support and hydraulic equalization) areperformed by the apparatus itself. On backwash, other advantages areapparent. The backwash stream leaves collector 26 at a uniformperimetrical rate and distribution. Any tendency to channel is avoidedbecause ow, of necessity, is at a high velocity due to the restrictedcross-section between wall 15 and wall it). There is more than enoughmass ilow volume to scour the entire cross-section of the annulus.

The heating and control functions also are affected in a manner whichsimultaneously achieves high efficiency and trouble-free operation, Whenthe unit is started, the pilots are lit and gas continues to ilowthrough pilot line 42 as long as the controller E permits. Thecontroller, as is customary, contains a safety pilot shut-off valvewhich automatically shuts off gas to burner 44 and their associatedpilots if there is an interruption to the flow of gas in line 40.Controller E also includes a snap-action bi-rnetallic thermostat whichsenses the temperature of water in line 2,9 and which cuts olf liow ofgas through feed line 43 when the temperature rises above a presetpoint. Thus, llow of gas to burners lift is an inverse on-oi function ofdischarge water temperature. Air to support combustion enters throughorifices 17 or, depending on whether the unit is ground-mounted or notinlets 22. Both of these may be properly adjusted for C02 content in thecombustion gas, and the gas is vented through hood 2l). The batllesreduce stack temperature so that hood Zt) is generally safe to touchbut, more important, the chimney il? at its hottest and most dangerouslevels is completely water jacketed by riser i3.

Heating the water prior to filtration, as is done in the embodimentshown, tends to make any salting-out oc cur within filter section Bwhere mineral deposits can be removed by the lter medium 2d. It shouldalso be noted that heat exchange occurs not only in coil 3d andassociated conduits 3l and 32 but also through walls l5 and head 118.

FGURE 3 illustrates a modilication of the invention which may beutilized in connection with the embodiment previously described, as wellas in connection with the axial water heater embodiments which will bedescribed below. Essentially the embodiment shown in FIGURE 3 includes avertical bypass line to connecting the two ends of coil 30. ln thebypass line is a by-pass valve 47, operated by an elongated stem 4B,which passes through combustion chamber sidewall l5 and filter chambersidewall liti with the aid of packing glands i192 Operation may beeffected by a valve handle Sti, or may be automatically controlled as afunction of temperature. When Valve 47 is closed all water coming fromthe pool through conduit 3?; passes through coil 3@ and is dischargedfrom goose-neel: riser 3l into filter section B, having been heated toits maximum extent. In brief, with the valve closed all of the waterwhich is heated is also ltered. However', with the valve 47 open little,if any, water passes through coil 3@ and, consequently, the mass rate offlow of water through heater C is great enough to minimize heating. Itis thus seen how this by-pass arrangement gives the operator anadditional degree of control over outlet water temperature, beyond thatavailable to him through the mere setting of controller E.

The embodiments described above have been described in detail and atlength. The embodiments which will now be described are generallysimilar except for those specilic differences which will be described indetail. Where nothing is said about details of construction, controls,ancillary equipment and the like these are to be taken as similar oridentical to those discussed above. lt is assumed that one skilled inthe art will, almost from the lgnres alone, have a ready comprehensionof the variants which will now be discussed.

lin FIGURES 4 and 5 an embodiment of the invention is shown wherein theilter section B while still in concentric relationship to the heaterlies along the longitudinal axis of the apparatus and where thecombustion chamber or heater C is mounted annularly thereabout. Withparticular reference to these figures, it will be observed that theshell A includes sidewalls 6d, a dished head 6l, and a chimney 62extending longitudinally upward therefrom. Lower wall portion 63 mayserve as legs for the unit and may also include variable-openingaireinlets 6d through which combustion air is admitted.

Heat is supplied by a suitable burner assembly D which may be, as shownof the perforated toroid type, or, inter ai or the type Shown inFIGURE 1. water heater C includes a plurality of fire-tubes 65 which aremounted between an upper tube sheet 66 and a lower tube sheet 67.Combustion gases flow upward through tubes 65, into the chamber definedby the interior of head dl and up 7 through chimney 62 which may, ifdesired, be suitably bafiied.

The filter section B is mounted on the longitudinal axis of thefilter-heater combination and includes a dished head d0, a generallycylindrical shell 69 and a dished bottom 70. Internally, the filter isprovided with a forarninous underdrain 71 which divides the interior ofthe filter into an upper inlet section 72 and a lower clear water outletsection 73. Section 72 contains a suitable filter medium 74, preferablysilicious in nature.

AS indicated by the arrows, water from the pool, corning through conduit75, enters the filter B above the waterfilter medium interface 76.Filter tail pipe 77 connects lower section 73 with the water side of theinterior space defined by tube sheets 66 and 67 and fire-tubes 05.I-Ieated water leaves this interior section and is returned to the poolthrough discharge pipe 78. As indicated, the shell A and the filter Bare suitably constructed with flanged heads so that access may be had totheir respective interiors for the purpose of re-tubing the heatersection and replacing the filter medium in the filter section E. Theabutment of tube sheets 66 and 67 against shell 69 may take the form ofa weldment or utilize conventional Water-tight expansion jointtechniques.

FIGURES 6 and 7, like FIGURES 4 and 5 represent an embodiment of theinvention wherein the filter section B also lies along the longitudinalaxis of the apparatus and where the water heater C is annularly mountedthereabout. Consequently, the part numbers for FIG- URES 4 to 7inclusive are identical except as to specific points of difference.

In the case of FIGURES 6 and 7 these differences relate to the patternof fiow and liquid treatment. Thus, as shown by the arrows in theembodiment shown of FIG- URE 6, water from the pool enters the unitthrough conduit 80 directly into the bottom of the interior spacedefined by tube sheets 66 and 07 and fire-tubes Heated water istransferred from the top of this interior section to the top of filter Bby shunt conduit 01 which penetrates wall 69. The clarified water fromthe filter is discharged directly to the pool via outlet conduit 82.With this embodiment, as is apparent, Water is heated prior tofiltration.

In the embodiments of the filter-heater combination of the inventionpreviously discussed the filters were of the sand, sand and gravel orsilicious filter medium type. In FIGURES 8 and 9, however, arerepresented embodiments of the invention which utilize filters of thediatomaceous earth type. In both of these figures the filter section Bis a core mounted on the longitudinal axis of the apparatus and thecombustion and water heater is annular and concentrically mounted aboutfilter section B. The differences between the embodiments shown inFIGURES 8 and 9 relate only to the sequence of the filter and heatingoperations. Consequently, the details of construction between these twoembodiments are minor and, further, FIGURE may be considered across-section which is representative of both embodiments.

Referring now, in detail, to FIGURES 8 and 9 the shell A includescylindrical sidewalls 90 having integral lower support portions 91 inwhich are provided a plurality of perimetrically spaced combustionair-inlets 92. The shell is fitted with a dished head 93, preferablyfiangedly attached to sidewalls 90 so as to permit retubing of the unit.The head 93 is also provided with a removable hatchway or manhole 94 topermit access to filter section B. Within the shell is provided an uppertube sheet 95 and a lower tube sheet 96 between which are mounted aplurality of fire-tubes 97. An off-set chimney 98, -mounted on dishedhead 93, vents combustion gases to the atmosphere. The burner assemblyD, and its controls are of the type previously described. As indicatedby the arrows, air enters inlets 92 and combustion gases leave the unitby rising upward through tubes 97, into the space above tube sheet 95and out through chimney 9S which may be suitably baffled.

The filter unit B may be of any suitable diatomaceous earth type but itis preferred to use that type of unit which is described in detail inthe co-pending patent application of Ira Silverman, being applicationNo. 234,162 filed Oct. 30, 1962, entitled, Liquid ClarificationApparatus, and now iatent No. 3,149,072, issued Sept. 15, 1964.

The reason for preferring this type of construction is that a given size(Le. diameter and height) filter section B can be provided with arelatively wide range of square feet of filtration surface. Thisiiexibility is available because it is possible, Within a given shellsize, to vary both the number of filter elements and the length of givenfilter elements. Means for achieving these desiderata are shown in thefigures, particularly in FIGURE 8. As shown therein, the filter sectionB comprises a cylindrical wall 99, a dished bottom 100, and a removabletop 101. The interior of the filter is divided into an inlet section 102and an outlet section 103 by a transverse header plate 104.-. Thisheader plate, in accordance with the preferred construction, is providedwith a plurality of nipples 105 (see FIG- URE 8) some of which areremovably capped as with cap 106. Upon all the other nipples areremovably mounted filter elements 107. Each of these elements is astacked, latticed structure made up of any desired number of interlockedmodules such as modules 108. Since the number of modules can be varied,even in the field, the height of any or all of filter elements 107 maybe adjusted to suit particular operating conditions. The moduleillustrated in FIGURE 8 comprises a thin horizontal annulus from whichdepends at least three tubular legs. The surface of the annulus remotefrom the dependent legs is provided with cored detents which preventcircumferential, radial and logitudinal displacement of one module withrespect to the other. Atop the latticed module construct, which performsno filtering in itself, is provided a tubular filter bag 109 which alsodoes no filtering but upon which a coating of diatomaceous earth isbuilt up, as is customary in the art. It is the coating of diatomaceousearth, deposited on the surface of filter bags 109, in turn supported bymodules 108, which performs the actual filtration. Additionally, helicalspacers 110 may be mounted on elements 107 at the end remote from plate104 to keep the elements 107 in continued parallel relationship despitethe build up of filter cake thereupon. While FIGURE 8 shows details ofthe preferred construction, any suitable diatomaceous earth filter maybe used in its place.

Turning now to the hydraulics of operation of the device in FIGURE V8,it will be noted that water from the swimming pool enters filter Bthrough inlet line 111. The water passes through a coating ofdiatomaceous earth on the surface of bags 109 to the interior ofelements 107 passing downwardly through nipples 105 into outlet section103. Fitting 112 carries this water into the water-side interior of thespace between tube sheets 95 and 96 and the exteriors of fire-tubes 97.Heated water rises through this section and is returned to the poolthrough outlet line 113. Thus, the embodiment shown in FIGURE 8 firstfilters the water in filter B and, thereafter, heats it.

Operation of the embodiment shown in FIGURE 9 is substantially similar.Here, however, water is first heated and then filtered. This is achievedby allowing water from the pool to enter the bottom of the water-sidespace between tube sheets 95 and 96 and the exterior of fire-tubes 9'7through an inlet line 114. Heated water rises within this section andpasses through cross-over conduit 115 into filter inlet section 102. Theheated water passes through the lter elements 107 into outlet section103 and is conveyed from there back to the pool through outlet conduit116.

FIGURES 11 to 14 inclusive show other embodiments of the filter-heatercombination of the invention wherein the filter is also of thediatomaceous earth type. In these embodiments, however, the waterheating chamber C is located on the longitudinal axis of the apparatuswhereas the filter section B is annular and mounted concentricallythereabout. FIGURE 11 represents an embodiment where- 9 in heating isperformed prior to filtration and FIGURE 13 represents an embodimentwherein heating is performed after filtration.

Turning now to FIGURES 11 to 14 inclusive it will be observed that theshells A comprise cylindrical sidewalls 120, dished heads 121, risers122, capped as at 123 and bottoms 124. This construction issubstantially identical to that shown in FIGURE 1. Filter section B isdivided into an inlet section 125 and an outlet section 126 by anannular transverse header plate 127 which is similar in function anddetails of construction to header plate 104 in FIGURE S. Mounted onheader plate 127 and perimetrically spaced thereabout are a plurality offilter elements 128 which may be identical in construction to filterelements 167. Flow from inlet section 125 to outlet section 126 isthrough filter elements 128 to their interior and thence, through header127 into the outlet section.

The combustion chamber or water heater C and burner assembly D in theseembodiments are identical to these components as described in FIGURE l,and, accordingly, the same part numbers have been used and the sameexplanation applies.

In FIGURES 11 and 12 water from the pool enters the apparatus throughinlet line 129 fiowing thence, through sidewall 15 into upwardlyextending helical coil 130. Coil 136 terminates in end portion 131 whichpenetrates chimney 19 into fiiter inlet section 125 and delivers heatedwater thereto. The efiiuent of filter outlet section 126 is returned tothe pool through discharge line 132.

In the embodiment shown in FIGURES 13 and 14, where filtration isperformed first, the discharge of pump 34 is conducted to the interiorof riser 122 by transfer conduit 135. Flow is down through the riser,into inlet section 125 and through filter elements 128 into outletsection 126. A transition piece 136 connects outlet section 126 withhelical coil 137. The coil terminates, as with a horizontal dischargeconduit 138 in a piece which penetrates from the interior of chimney 19to the exterior of the device and thus returns filtered and heated waterto the pool. The coils shown in FIGURES 11 and 14 inclusive may beprovided with hydraulic by-pass arrangements as illustrated in FIGURE 3and like the other coils are removable for ease of replacement.

While the apparatus has been described with respect to a gaseous fuel(such as natural gas, manufactured gas, mixtures thereof, bottled gasand the like) it lends itself to the use of oil-fired equipment. Whilethis necessitates some modifications with respect to the water heater C(e.g. provision of a refractory lining) and the control system (e.g.ignition control from a stack relay, activation of burner by anaquastat, etc.) the fundamentals of the apparatus are unchanged.

Although our invention has been described in considerable detail, suchdescription is intended to be illustrative rather than limiting sincethe invention may be variously embodied and, therefore, the scope of theinvention is to be determined only by the appended claims.

Having described our invention, we claim:

1. A swimming pool filter-heater combination cornprising a diatomaceousearth filter having a plurality of separate filter elements, a directfired water heater mounted concentrically with respect to said filterand in direct heat exchange relationship therewith, said heaterincluding a combustion chamber and a chimney; conduit means connectingsaid heater to a pool, conduit means connecting said heater to saidfilter for conducting water from one to the other; and conduit meansconnecting said filter to a pool; whereby cold unfiltered Waterwithdrawn from a pool is returned thereto in heated and filteredcondition.

2. A swimming pool filter-heater combination cornprising a water filter,an annular direct fired water heater mounted concentrically indirectheat exchange relationship about said lter, said heater including acombustion chamber and a chimney; conduit means connecting said heaterto a pool, conduit means connecting said heater to said filter forconducting water from one to the other and conduit means connecting saidfilter to a pool; whereby cold unfiltered water withdrawn from a pool isreturned thereto in heated and filtered condition.

`3. A swimming pool lter-heater combination comprising a water filter, adirect fired water heater mounted concentrically with respect to saidlilter and having a wall in common therewith through which heat istransmitted from combustion gas to liquid, said heater further includinga combustion chamber and a chimney; conduit means for conducting coldunfiltered water coming from a swimming pool to said heater, conduitmeans for conducting heated unfiltered water from sai-d heater to saidfilter and conduit means for conducting heated and filtered water fromsaid filter back to a swimming pool.

4. The swimming pool filter-heater combination of i claim 3 whereinthere are provided a central Water heater including `a heating coil andburner means positioned beneath said coil; an annular filter mountedupon and supported by said water heater and concentric therewithincluding an annular collector; a conduit for conducting water comingfrom a swimming pool to the inlet of said coil; a conduit for conductingheated water from the outlet of said coil to the top of said filter; aconduit for conducting heater and filtered water from said collectorback toward a pool, sai-d filter-heater permitting direct transfer ofheat from said water heater into said filter.

5. The apparatus of claim 4 wherein means are provided for permittingless water to flow through said coil than through said filter.

6. The swimming pool filter-heater combination of claim 2 having acentral sand filter of generally cylindrical configuration; fuel burnermeans operatively associated with said annular heater.

7. The filter-heater combination of claim 6 wherein said heater includesa pair of transverse annular tube sheets longitudinally spaced apart anda plurality of longitudinally extending tubes extending therebetween,Water passing on one side of said tubes and combustion gases passing .onthe other side thereof.

8. A swimming pool filter-heater combination comprising a centraldiatomaceous earth filter of generally cylindrical configuration havinga plurality of `separate filter elements; an outer annular direct firedwater heater mounted concentrically about said filter including acombustion chamber and a chimney; fuel burner means mounted in saidcombustion chamber and operatively associated with said heater; conduitmeans connecting said lheater with a swimming pool; conduit meansconnecting `said filter with said swimming pool and conduit meansconnecting said filter and said heater whereby cold unfiltered Waterwithdrawn from the pool is returned thereto heated and filtered.

9. The filter-heater combination of claim 3 which further includes,within the filter section, a transverse header plate including aplurality of nipples, filter elements removably mounted on some of saidnipples and flow-blocking caps mounted on the remaining nipples, eachfilter element being of stacked latticed modular construction, saidconstruction providing two separate means for variatie-n of the numberof square feet of filter surface in a given filter.

1i). The filter-heater combination of claim 9 wherein said heaterincludes a pair of transverse annular tube sheets longitudinally spacedapart and a plurality of longitudinally extending tubes therebetween,water passing on one side of said tubes and combustion gases passing onthe other side thereof.

11. The filter-heater combination of claim S wherein said heaterincludes a pair of transverse annular tube sheets longitudinally spacedapart and a plurality `of longitudinally extending tubes therebetween,water passing on one side of said tubes and combustion gases passing onthe other side thereof.

12. The swimming pool filter-heater combination of claim 1 wherein thewater heater is centrally located and has a heating coil and burnermeans operatively assooiated therewith; said filter is an annulardiatomaeeous earth filter having a plurality of separate filter elementsmounted concentrically about said heater.

13. The swimming pool filter-heater of claim 12 wherein means areprovided for permitting less water to flow through said coil thanthrough said filter.

14. The swimming pool filter-heater combination of claim 12 whichfurther includes, within said filter section, a transverse annularheader plate including a plurality of nipples, said filter elementsbeing removably mounted on some of said nipples and flow-blocking capsmounted on the remainder of said nipples, each filter element being ofstacked latticed modular construction, said construction providing twoseparate means for variations of the number of square feet of filtersurface in a given filter.

15. The filter-heater combination of claim 1 wherein said water heateris centrally located and said filter is annular, being mounted aboutsaid water heater.

16. The filter-heater combination of claim 15 wherein water from a poolis first heated and thereafter ltered.

17. The filter-heater combination of claim 15 wherein water from a poolis first filtered and thereafter heated.

13. The filter-heater combination of claim 1 wherein said filter iscentrally located and said heater is annular, being mounted about saidfilter.

19. The filter-heater combination o-f claim 18 wherein water from a poolis first heated and thereafter filtered.

20. The filter-heater combination of claim 18 wherein water from a poolis first filtered and thereafter heated.

21. The filter-heater combination of claim 2 wherein said filter is adiatomaceous earth filter having a plurality of separate filterelements.

22. The filter-heater combination of claim 21 wherein water from a `poolis first filtered and thereafter heated.

23. The filter-heater combination of claim 21 wherein CTI 12 water froma pool is first filtered and thereafter heated.

24. The filter-heater combination of claim 2 wherein said filter is asand filter.

25. The filter-heater combination of claim 24 wherein water from a poolis first heated and thereafter filtered.

26. The filter-heater combination of claim 24 wherein water `from a poolis first filtered and thereafter heated.

27. The filter-heater combination of claim 3 wherein said filter is adiatomaceous earth filter having a plurality of separate filterelements.

28. The filter-heater combination of claim 27 wherein said filter iscentrally located and said heater is annular, being mounted about saidfilter.

29. The filter-heater combination of claim 27 wherein said water heateris centrally located and said filter is annular, being mounted aboutsaid water heater.

30. The filterheater combination of claim 3 wherein said filter is asand lter.

31. The filter-heater combination of claim 30 wherein said filter iscentrally located and said heater is annular, being mounted about saidfilter.

32. The filter-heater combination of claim 30 wherein said heater iscentrally located and said filter is annular, being mounted about saidheater.

References Cited UNITED STATES PATENTS 1,144,327 6/1915 Greth 210-169 X2,960,232 11/1960 Gillette 210-169 3,072,134 l/ 1963 Williamson.

FOREIGN PATENTS 6,171 12/ 1901 Austria.

7,217 1903 Great Britain.

REUBEN FRlEDMAN, Primary Examiner.

F. MEDLEY, Assistant Examiner.

1. A SWIMMING POOL FILTER-HEATER COMBINATION COMPRISING A DIATOMACEOUSEARTH FILTER HAVING A PLURALITY OF SEPARATE FILTER ELEMENTS, A DIRECTFIRED WATER HEATER MOUNTED CONCENTRICALLY WITH RESPECT TO SAID FILTERAND IN DIRECT HEAT EXCAHNGE RELATIONSHIP THEREWITH, SAID HEATERINCLUDING A COMBUSTION CHAMBER AND A CHIMMEY; CONDUIT MEANS CONNECTING AHEATER TO A POOL, CONDUIT MEANS CONNECTING SAID HEATER TO SAID FILTERFOR CONDUCTING WATER